Microstructure glass-ceramic

Household waste, 25 864 House-of-cards glass-ceramic microstructure, 12 635 Housewares, LLDPE, 20 207-203 Housewrap, 17 482 Housings, for cartridge filters, 11 369 Hoveya-Grubbs catalysts, 26 934 H-phosphonate DNA synthesis method, 17 624-625... 

Sun, E.Y., Nutt, S.R. and Brennan, J.J. (1994). Interfacial microstructure and chemistry of SiC/BN dual-coated Nicalon-fiber reinforced glass-ceramic matrix composites. J. Am. Ceram. Soc. 77, 1329-1239. 

Figure 1.52 Micro structure of a typical glass ceramic with a fine grain size, minimal residual glass, and little porosity (P). From W. E. Lee and W. M. Rainforth, Ceramic Microstructures. p. 59 Copyright 1994 by William E. Lee and W. Mark Rainforth, with kind permission of Kluwer Academic Publishers.

The development of the principles of nucleation and growth early in the twentieth century (2) ultimately led to the discovery that certain nudeating agents can induce a glass to crystallize with a fine-grained, highly uniform microstructure that offers unique physical properties (3). The first commercial glass-ceramic products were missile nose cones and cookware. 

There are three key variables in the design of a glass-ceramic the glass composition, the glass-ceramic phase assemblage, and the nature of the crystalline microstructure. 

Fig. 3. Replica electron micrograph showing "house-of-cards" microstructure in a machinable fluormica glass-ceramic (white bar = 10 /xm).

Fig. 6. Microstructure of transparent p-quartz solid solution glass-ceramic as...

Stryjak and McMillan (1978) demonstrated increased hardness of the recrystallized material (Table 5.9), testing the properties of spinel glass-ceramics from the Zn0-Al203-Si02 system, with Zr02 admixture as the crystallization nucleator, in combination with the microstructure of glasses... 

Carter, S., Ponton, C.B., Rawlings, R.D., Rogers, PS. (1988), Microstructure, chemistry, elastic properties and internal friction of Silceram glass-ceramics , 7. Mater. Sci., 23, 2622- 2630. 

Fig. 8.15 Changes in interface microstructure in SiC fiber-reinforced BMAS glass-ceramic composites induced by exposure to high temperature oxidizing environments, (a) After tensile stress-rupture experiment at 1100°C, the 90° fibers show a distinct dual layer at the BN coating-fiber interface, (b) After thermal aging for 500 h at 1200°C, a subtle double layer appears at the same site, (c) Near the composite surface, the effects of thermal aging (and oxidation) are more pronounced.24...

E. Y. Sun, S. R. Nutt, and J. J. Brennan, Interfacial Microstructure and Chemistry of SiC/BN Dual-Coated Nicalon Fiber Reinforced Glass-Ceramic Matrix Composites, J. Am. Ceram. Soc., 77[5], 1329-1339 (1994). 

R. E. Loehman, T. J. Headley, Design of high thermal expansion glass-ceramics through microstructural control, in Ceramic Microstructures 86 Role of Interfaces, J. A. Pask and A. G. Evans, eds.. Plenum Press, New York, 1987. 

Applying fracture mechanics techniques to characterize brittle materials has become an important subfield of materials science, and a reasonable understanding of the relation between toughness, composition, and microstructure is available. Silicate glasses have toughness values of 0.7-1,0 MPam, alumina ceramics values of 4-5 MPam, and glass ceramics values of 1-4 MPam, (the fracture toughness of metals is often > 50 MPam "),... 

Glass-ceramics are processed in the same way as glasses, but are then given a further heat treatment to nucleate and grow a crystalline phase, such that the final microstructure is composed of crystals with a glass phase in between. The possibility of tailoring both the initial composition and size and the volume fraction of the crystalline phase allows for precise tailoring of properties. 

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